CN111564593B - Diaphragm, diaphragm roll, battery core and power lithium battery - Google Patents

Diaphragm, diaphragm roll, battery core and power lithium battery Download PDF

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Publication number
CN111564593B
CN111564593B CN202010503541.1A CN202010503541A CN111564593B CN 111564593 B CN111564593 B CN 111564593B CN 202010503541 A CN202010503541 A CN 202010503541A CN 111564593 B CN111564593 B CN 111564593B
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Prior art keywords
battery
diaphragm
porous base
coating
bonding layer
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CN111564593A (en
Inventor
平翔
华超
钟宝成
叶小宝
杨雪梅
陈秀峰
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Jiangsu Xingyuan New Material Technology Co ltd
Shenzhen Senior Technology Material Co Ltd
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Jiangsu Xingyuan New Material Technology Co ltd
Shenzhen Senior Technology Material Co Ltd
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Priority to CN202010503541.1A priority Critical patent/CN111564593B/en
Publication of CN111564593A publication Critical patent/CN111564593A/en
Priority to US18/000,654 priority patent/US20230198098A1/en
Priority to PCT/CN2021/108715 priority patent/WO2021244672A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H01M50/461—Separators, membranes or diaphragms characterised by their combination with electrodes with adhesive layers between electrodes and separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/42—Acrylic resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H01M50/434—Ceramics
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/44—Fibrous material
    • H—ELECTRICITY
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    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • H—ELECTRICITY
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    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Ceramic Engineering (AREA)
  • Composite Materials (AREA)
  • Cell Separators (AREA)

Abstract

The application relates to the field of lithium ion batteries, in particular to a diaphragm, a diaphragm roll, an electric core and a power lithium battery. The separator includes a porous base film and an adhesive layer; along the preset direction of the porous base membrane, the surface of the porous base membrane comprises a middle blank area and coating areas at two ends; the tie layer is applied in two coated areas. Through coating the tie coat at the both ends on porous base film surface, can be at lithium cell electricity core equipment and forming process for the tie coat plays and contacts and bond with the both ends of the inside negative pole piece of lithium cell electricity core, guarantee effectively that the lithium cell bears sufficient tension, pressure and vibrations in equipment, vibration test and long-term circulation process, avoid because of between the battery just, the negative pole piece, relative motion between electric core and the casing, the yield that leads to is low, little short circuit, self-discharge, internal resistance risees and welding utmost point ear position is not hard up or bad consequences such as destruction.

Description

Diaphragm, diaphragm roll, battery core and power lithium battery
Technical Field
The application relates to the field of lithium ion batteries, in particular to a diaphragm, a diaphragm roll, an electric core and a power lithium battery.
Background
With the development of electric automobiles, the requirements on the energy density and the safety performance of power lithium batteries are higher and higher, and from the perspective of the technical principle of lithium batteries, how to effectively and uniformly solve the two important performances which are contradictory with each other is a big problem to be solved in the current lithium battery science and industry.
In a traditional power lithium battery system, a battery cell is assembled into a module, and then the module is installed in a battery pack, so that a three-level assembly mode of battery cell-module-battery pack is formed. Wherein, the design form of constituteing the module with the monomer little electric core is based on the level restriction of industry earlier stage battery material and battery engineering ability, and very difficult large batch makes the good great capacity electric core of uniformity, along with the promotion of materials science and battery engineering ability, cancels shared volume and weight of module, bypasses the module, and the direct electric core of using constitutes the battery package and has just become the trend of a power battery development to this improves the energy density of lithium cell greatly through structural optimization. Statistics show that the space utilization rate of the power battery pack designed by the technology is improved by about 20%, related parts are reduced by about 40%, and the battery production efficiency is improved by about 50%. Therefore, the size and the weight saved by the module are saved, the electric quantity can be increased, and the endurance is improved. Therefore, the design mode from the battery core to the battery pack can have a more simplified production flow and higher production efficiency, the manufacturing cost of the power battery can be greatly reduced, and the method is an effective engineering solution for improving the overall technology of the power battery. However, the technical problems in many aspects such as a large number of structural designs and processes need to be solved in the back of the engineering solution.
At present, power battery's electric core mainly divide into cylinder, soft package and square battery from structural design, under the prerequisite that does not change current material and electrochemistry system, in order to realize system energy density's promotion, reduces the module or cancels the module, and main technical means is exactly the capacity that increases monomer electric core, embodies on monomer electric core, is exactly the change of its size form, including the length, the width and the thickness of electric core. Due to the change in battery dimensions, especially the large increase in the width direction, serious technical challenges are posed to the assembly and long-term use stability of the cell structure. In addition, in the long-term use process of the power battery pack, due to the influence of vibration and internal local resonance, relative motion is easy to occur between the positive pole piece and the negative pole piece of the battery, between the battery core and the shell, the welded pole ear position is easy to loosen or damage, the phenomena of unstable structure and performance occur, and thus the battery is easy to have the phenomena of micro short circuit, self discharge, internal resistance increase and the like in the production and use processes, and the yield and reliability of the battery production are low.
Disclosure of Invention
An object of the embodiment of the application is to provide a diaphragm, a diaphragm roll, a battery core and a power lithium battery.
In a first aspect, the present application provides a separator comprising a porous base film and a bonding layer;
along the preset direction of the porous base membrane, the surface of the porous base membrane comprises a middle blank area and coating areas at two ends;
the adhesive layer is coated on the coating area at both ends.
This diaphragm through the both ends coating tie coat on porous base film surface, can be in lithium battery electricity core equipment and forming process for the tie coat play with the inside both ends contact and the bonding of negative pole piece of lithium battery electricity core, and also can bond each other between the tie coat when the rolling, consequently, this diaphragm can make the fixed position between the battery pole piece and compact, thereby makes battery pole piece, diaphragm become a whole. Particularly for large-size power lithium batteries, the lithium battery can be effectively ensured to bear enough tension, pressure and vibration in the processes of assembly, vibration test and long-term circulation, and adverse effects of low yield, micro short circuit, self discharge, internal resistance increase, loosening or damage of welding electrode lugs and the like caused by relative motion between the positive electrode plate and the negative electrode plate of the battery and between the battery core and the shell are avoided.
In a second aspect, the present application provides a separator roll, which is formed by rolling the separator roll perpendicular to a predetermined direction.
In a third aspect, the present application provides a battery cell, including the aforementioned separator;
the negative plate is arranged on one side of the diaphragm, and two ends of the negative plate are bonded on the bonding layer coated on the surface of the diaphragm; and
and the positive plate is positioned on the other side of the diaphragm and is overlapped with the blank area of the diaphragm.
The battery cell can effectively ensure that the lithium battery bears enough tension, pressure and vibration in the assembling, vibration testing and long-term circulating processes, and avoids the adverse effects of low yield, micro short circuit, self discharge, rising of internal resistance, loosening or damage of welding electrode ear positions and the like caused by relative motion between the battery positive and negative pole pieces and between the battery cell and the shell. The battery core can be used for preparing a large-size battery and has long-term circulation stability.
Further, because the tie coat does not have the hole, can influence lithium ion's transmission efficiency, and then influence the performance of positive electrode material capacity, and the middle blank region and the laminating of positive pole piece on two surfaces of diaphragm that this application provided, the tie coat does not contact with the active material on the inside positive pole piece of lithium cell electricity core promptly, consequently can not cause the influence to the transmission efficiency of battery. This diaphragm can not lead to lithium cell equipment too complicated, and processing cost is lower, and can greatly improve the stability of the inside electric core of battery, guarantees the long-term endless stability of lithium cell.
In a fourth aspect, the present application provides a power lithium battery, which includes the foregoing battery core.
The power lithium battery has long-term circulation stability.
Drawings
In order to more clearly explain the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that for those skilled in the art, other related drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a schematic illustration of a first composite membrane provided in embodiments herein;
FIG. 2 is a schematic view of a second composite separator provided by embodiments of the present application;
FIG. 3 is a schematic illustration of a third composite membrane provided in accordance with embodiments of the present application;
FIG. 4 is a schematic illustration of a fourth composite membrane provided in accordance with embodiments of the present application;
fig. 5 is a schematic diagram of a battery cell provided in an embodiment of the present application.
Icon: 100-porous base membrane; 200-a tie layer; 101-blank area; 201-a tie layer; 102-blank area; 202-a bonding layer; 103-blank area; 203-a tie layer; 104-blank area.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
The embodiment of the application provides a diaphragm, which comprises a porous base membrane and a bonding layer;
along the preset direction (arrow direction in fig. 1) of the porous base membrane, the surface of the porous base membrane comprises a middle blank area and coating areas at two ends;
the adhesive layer is coated on the coating area at both ends.
This diaphragm through the both ends coating tie coat on porous base film surface, can be in lithium battery electricity core equipment and forming process for the tie coat play with the inside both ends contact and the bonding of negative pole piece of lithium battery electricity core, and also can bond each other between the tie coat, consequently, this diaphragm can make the fixed position between the battery pole piece and compact, thereby make battery pole piece, diaphragm become a whole. Particularly for large-size power lithium batteries, the lithium battery can be effectively ensured to bear enough tension, pressure and vibration in the processes of assembly, vibration test and long-term circulation, and adverse effects of low yield, micro short circuit, self discharge, internal resistance increase, loosening or damage of welding electrode lugs and the like caused by relative motion between the positive electrode plate and the negative electrode plate of the battery and between the battery core and the shell are avoided.
Further, in some embodiments of the present application, the porous base film is a single layer. Further optionally, the material of the porous base film is selected from one or more of polyethylene, polypropylene, polyethylene terephthalate, polyamide, polyimide, and PET non-woven fabric.
Further, in some embodiments of the present application, the porous base membrane is a multilayer. The porous base membrane is made of polyethylene or polypropylene with different molecular weights and different melt indexes.
Further, in some embodiments of the present application, the porous base membrane is a multilayer. The porous base membrane is made of polyethylene and polypropylene with different molecular weights and different melt indexes. Illustratively, the porous base membrane is three layers.
Further, the thickness of the porous base film is in the range of 5 μm to 30 μm.
Further optionally, the porous base membrane has a thickness in a range of 6 μm to 28 μm.
Further optionally, the porous base membrane has a thickness in a range of 10 μm to 25 μm.
Illustratively, the thickness of the porous base membrane is 15 μm, 18 μm, or 20 μm.
Further, the porosity of the porous base film is in the range of 20% to 70%.
Further optionally, the porosity of the porous base membrane is in the range of 25% to 65%.
Further optionally, the porosity of the porous base membrane is in the range of 30% to 60%.
Illustratively, the porous base membrane has a porosity of 35%, 40%, 45%, or 50%.
Further, the raw material of the bonding layer includes an organic substance.
Further optionally, the organic substance is selected from at least one of polyacrylate, polyacrylic acid, polyacrylate, styrene-butadiene rubber, epoxy resin, amino resin, polyamide, polyethyleneimine, polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyvinylidene fluoride-tetrafluoroethylene copolymer.
Further optionally, the raw material of the adhesive layer further comprises at least one of sodium carboxymethyl cellulose and sodium alginate. Illustratively, at least one of the foregoing organic substances is selected to be compounded with at least one of sodium carboxymethylcellulose and sodium alginate to prepare the adhesive layer.
Furthermore, the organic matter accounts for 10-100% of the total weight of the bonding layer in percentage by weight.
Further optionally, the organic matter accounts for 15-95% of the total weight of the bonding layer in percentage by weight.
Further optionally, the organic matter accounts for 20-80% of the total weight of the bonding layer in percentage by weight.
Illustratively, the bonding layer comprises 100% organic.
In some embodiments of the present application, the raw material of the bonding layer includes an organic material and an inorganic material. The addition of inorganic substances can reduce static electricity generated by the adhesive layer to a certain extent and improve some problems caused by static electricity during use, but the excessive addition of inorganic substances can affect the exertion of adhesive force of the adhesive layer.
Furthermore, the inorganic matter accounts for 0-90% of the total weight of the bonding layer in percentage by weight.
When the amount of the inorganic substance is within the above range, the problem of static electricity during use can be effectively improved and a good adhesion effect can be secured.
Further optionally, the inorganic matter accounts for 5-85% of the total weight of the bonding layer in percentage by weight.
Further optionally, the inorganic matter accounts for 10-80% of the total weight of the bonding layer in percentage by weight.
Illustratively, the bonding layer comprises, in weight percent, 20% inorganic and 80% organic; or the bonding layer comprises 50% inorganic matter and 50% organic matter.
Further, the inorganic substance is selected from one or more of alumina, titanium oxide, zinc oxide, calcium oxide, magnesium oxide, zirconium oxide and boehmite.
Furthermore, the granularity D50 of the inorganic substance ranges from 0.1 to 2.0 μm.
Further optionally, the particle size D50 of the inorganic substance is in a range of 0.5-1.8 μm.
Further optionally, the particle size D50 of the inorganic substance is 1-1.5 μm.
Illustratively, the inorganic substance has a particle size D50 of 0.8 μm, 1.2 μm, or 1.4. mu.m.
Further, the dimension of the coated area in the preset direction (width d1 in fig. 1) is between 2mm and 15 mm; the size of the blank area (width d2 in fig. 1) in the preset direction is between 50mm and 1200 mm.
Further, the size of the coating area along the preset direction is between 3mm and 14 mm; the size of the blank area along the preset direction is between 100mm and 1100 mm.
Further, the size of the coating area along the preset direction is between 4mm and 13 mm; the size of the blank area along the preset direction is between 500mm and 1000 mm.
Illustratively, the size of the coated area in the preset direction is 5mm, 8mm or 10 mm; the size of the blank area along the preset direction is 200mm, 400mm, 600mm or 800 mm.
Further optionally, the adhesive layers of the coated areas at both ends are symmetrical and equal in size.
Further, the thickness of the adhesive layer is 0.5 to 4 μm.
Further optionally, the adhesive layer has a thickness of 1 μm to 3.5 μm.
Further optionally, the bonding layer has a thickness of 1.5 μm to 3.0 μm.
Illustratively, the adhesive layer has a thickness of 2.0 μm, 2.5 μm, 2.6 μm, 2.8 μm, or 3.2 μm.
Further, the bonding layer is a continuous coating layer or a discontinuous coating layer.
Further, the discontinuous coating layers are coated at intervals along a preset direction. The non-continuous coating layer comprises a plurality of spaced strip-shaped coatings, point-shaped coatings, block-shaped coatings or bent-shaped coatings. For example, a plurality of serpentine shaped coatings are applied at intervals.
Referring to fig. 4, further, a direction perpendicular to the preset direction is an MD direction. When the discontinuous coating layer is a strip coating, the included angle alpha formed by the strip coating and the MD direction is between 10 and 170 degrees, but not 90 degrees.
Further optionally, when the discontinuous coating layer is a strip coating, an included angle formed between the strip coating and the MD direction is between 30 ° and 120 °.
Because the end parts of the two surfaces of the diaphragm are coated with the bonding layers, when coating and rolling are carried out, because the two ends are thick and the middle is thin, after the rolling length reaches a certain length, the stress of the end parts is possibly overlarge, the two ends adopt the coatings with the discontinuous structures, the concentrated stress of the end parts can be partially dispersed, the rolling length is increased, the coating and using efficiency is further improved, and the manufacturing cost is reduced.
Further, when the bonding layer is a discontinuous coating layer, the coverage rate of the bonding layer in a coating area is between 10% and 90%.
Further optionally, the coverage of the tie layer in the coated area is between 40% and 80%.
Further optionally, the coverage of the tie layer in the coated area is between 50% and 70%.
Illustratively, the coverage of the adhesive layer in the coated area is 55%, 60%, 65%, 75%, or the like.
When the coverage of the bonding layer is too low, the content of the polymer is too low, and the bonding force with two ends of the negative electrode of the lithium battery is too low, so that the bonding effect cannot be effectively realized. If the coverage rate is too high, the concentrated stress at the end part can not be well dispersed, and the improvement effect on the rolling length and the use efficiency is not obvious. In the coverage rate range, the concentrated stress at the end part can be effectively dispersed, and the rolling length and the use efficiency are well improved.
Further, referring to fig. 1, in some embodiments of the present application, a septum is provided. The separator includes a porous base film 100 and a bonding layer 200. Further, both surfaces of the porous base film 100 are coated with the adhesive layer 200. The adhesive layers 200 are coated on both ends of the porous base film 100, and both surfaces are coated with the adhesive layers 200. The middle region of the porous base film 100 is a blank region 101. The adhesive layer 200 is applied continuously. In fig. 1, all 4 adhesive layers 200 are continuous pure adhesive layers, and the width of the blank area is 600 mm. The adhesive layer 200 comprises only organic materials selected from the group consisting of polyacrylate, sodium carboxymethylcellulose, polyvinylidene fluoride, and polyvinylidene fluoride-hexafluoropropylene copolymer. The thickness of tie coat 200 is 2um, and the value of its unilateral width is 10 mm. The porous base film 100 is a three-layer polypropylene separator film composed of different molecular weights and different melt indexes.
In other alternative embodiments of the present application, the adhesive layer 200 may be coated on only one surface of the porous base film 100.
Further, referring to fig. 2, in some embodiments of the present application, a septum is provided. It is substantially the same as the separator provided in fig. 1, except that the adhesive layer 201 is a continuous pure polymer and inorganic substance mixed adhesive layer. Wherein the polymer accounts for 80 wt%, the inorganic matter accounts for 20 wt%, and the width of the middle blank region 102 is 600 mm. The porous base membrane 100 is a three-layer polypropylene/polyethylene/polypropylene separator membrane of different molecular weight, different melt index composition. The thickness of the bonding layer 201 is 2um, and the value of the unilateral width is 10 mm. The organic matter in the bonding layer 201 is selected from the composition of polyacrylate, sodium carboxymethylcellulose, polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer, the inorganic matter is selected from alumina, and the granularity D50 is 0.6 um.
Further, referring to fig. 3, in some embodiments of the present application, a septum is provided. Which is substantially the same as that provided for the separator of figure 1, except that the adhesive layer 202 is a non-continuous point-like pure adhesive layer. The coverage of the inside of the coated area is 60% and the width of the blank area 103 is 600 mm. The material of the porous base film 100 is selected from a single layer polypropylene separation film composed of different molecular weights and different melt indexes. The thickness of the adhesive layer 202 is 1.7um, and the value of the unilateral width is 15 mm. The adhesive layer 202 comprises only organic substances selected from the group consisting of polyacrylate, sodium carboxymethylcellulose, polyvinylidene fluoride, and polyvinylidene fluoride-hexafluoropropylene copolymer.
Further, referring to fig. 4, in some embodiments of the present application, a septum is provided. It is essentially the same as that provided in figure 1, except that the adhesive layer 203 is a non-continuous stripe of a pure adhesive layer. The coverage of the inside of the coating region was 60%, and the angle α formed by the stripe-shaped adhesive layer and the MD direction of the porous base film 100 was 45 °, and the width of the blank region 104 was 600 mm. The material of the porous base film 100 is selected from three layers of polypropylene barrier films consisting of different molecular weights and different melt indexes. The thickness of tie coat 203 is 2.3um, and the value of its unilateral width is 7 mm. The adhesive layer 203 only contains organic substances selected from the group consisting of polyacrylate, sodium carboxymethylcellulose, polyvinylidene fluoride, and polyvinylidene fluoride-hexafluoropropylene copolymer.
Some embodiments of the present application further provide a membrane roll, which is formed by rolling the membrane provided by the foregoing embodiments in a direction perpendicular to the preset direction.
Some embodiments of the present application also provide a battery cell, including the separator, the negative electrode sheet, and the positive electrode sheet provided in the foregoing embodiments.
The negative plate is arranged on one side of the diaphragm, and two ends of the negative plate are bonded on the bonding layer coated on the surface of the diaphragm.
The positive plate is positioned on the other side of the diaphragm, and the positive plate is overlapped with the blank area of the diaphragm.
The bonding layers at the two ends of the diaphragm play a role in bonding with the two ends of the lithium battery negative pole piece and bonding the bonding layers with each other, so that the positions of the battery pole pieces are fixed and compact, and the battery pole piece and the diaphragm are integrated. Particularly for large-size laminated batteries, the lithium battery can bear enough tension, pressure and vibration in the processes of assembly, vibration test and long-term circulation, and adverse effects of low yield, micro short circuit, self discharge, internal resistance increase, loosening or damage of welding electrode lugs and the like caused by relative motion between the positive electrode plate and the negative electrode plate of the battery and between the battery core and the shell are avoided.
Further, the tie coat can influence lithium ion's transmission efficiency because there is not the hole, and then influences the performance of positive electrode material capacity, and the middle blank region and the laminating of positive pole piece on two surfaces of diaphragm that this application provided, the tie coat does not contact with the active material on the inside positive pole piece of lithium cell electricity core promptly, consequently can not lead to the fact the influence to the transmission efficiency of battery. This diaphragm can not lead to lithium cell equipment too complicated, and processing cost is lower, and can greatly improve the stability of the inside electric core of battery, guarantees the long-term endless stability of lithium cell.
In some embodiments of the present application, the cell can be used in a large size laminated battery. Referring to fig. 5, when the battery core is assembled and molded, the positive electrode plate is located on one side of the diaphragm, and the positive electrode plate is attached to the blank area of the diaphragm (the size of the positive electrode plate is smaller than that of the diaphragm), so that the positive electrode plate is not in contact with the adhesive layer of the diaphragm, and therefore, the positive electrode plate is not in contact with the active material on the positive electrode plate, and the electrical property of the battery is not affected. The negative pole piece and the diaphragm are equal in size (can be slightly smaller than the diaphragm according to the requirement). The negative pole piece is located on the other side of the separator (below the separator, not shown in fig. 5).
Furthermore, the width d1 of the bonding layers at the two ends of the diaphragm is between 2mm and 15 mm.
The bonding layers at the two ends of the diaphragm firmly bond the diaphragm and the negative pole piece together, so that the lithium battery can bear enough tension, pressure and vibration in the processes of assembly, vibration test and long-term circulation, and adverse consequences such as low yield, micro short circuit, self discharge, rise of internal resistance, loosening or damage of welding pole ear positions and the like caused by relative motion between the positive pole piece and the negative pole piece of the battery and between the battery core and the shell are avoided.
Some embodiments of the present application also provide a power lithium battery, which includes the battery cell provided in the foregoing embodiments.
According to the power lithium battery, the battery cell is arranged, so that the large-size power lithium battery can bear enough tension, pressure and vibration in the assembling, vibration testing and long-term circulating processes, and the long-term circulating performance and the battery safety are improved.
The features and properties of the present application will be described in detail below with reference to examples and comparative examples.
Example 1
Provided is a power lithium battery, which is prepared by the following steps:
preparation of a negative electrode: adding graphite, conductive carbon black, a thickener sodium carboxymethyl cellulose and a binder styrene butadiene rubber emulsion into deionized water according to a mass ratio of 96:1:1:2, stirring and dispersing uniformly in a stirrer, filtering by using a 150-mesh screen to obtain required negative electrode slurry, and then coating, cold pressing and slitting to prepare a negative electrode sheet.
Preparation of the positive electrode: adding the lithium iron phosphate, the conductive agent and the adhesive polyvinylidene fluoride into N-methyl pyrrolidone (NMP) according to the mass ratio of 97:1:2, stirring and dispersing uniformly in a stirrer, filtering by using a 150-mesh screen to obtain required anode slurry, and then coating, cold pressing and slitting to prepare the anode sheet.
Preparing electrolyte: preparing a mixed solvent from ethylene carbonate EC, propylene carbonate PC and dimethyl carbonate DMC according to the volume ratio of 3:3:4, then adding a relevant additive and lithium hexafluorophosphate (LiPF6), preparing the concentration of LiPF6 to be 1M, and uniformly stirring to obtain the electrolyte.
Preparing a diaphragm: adding deionized water into polyacrylate, sodium carboxymethylcellulose, polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer according to the mass ratio of 6:1:10:83, stirring and dispersing uniformly in a stirrer, filtering by using a 150-mesh screen to obtain required slurry, coating the slurry on two end faces of one surface of an isolating membrane through gravure coating, and drying to form a single-sided continuous pure bonding layer. The three-layer polypropylene porous base membrane of 18um is selected for use to the substrate, the thickness of the pure tie coat of continuous type is 2um, and the value of its unilateral width is 10mm, and the blank space width of barrier film middle part is 600 mm.
Assembling the battery: and laminating the negative pole piece, the isolating membrane and the positive pole piece into a battery core, packaging the battery core by using an aluminum-plastic composite membrane, baking the battery core in a vacuum state to remove moisture, injecting quantitative electrolyte, and performing formation and capacity test on the battery to obtain the square flexible package lithium ion battery with the thickness, width and length of 25mm, 65mm and 610 mm. The battery pack is directly assembled by the battery cells according to a certain mode for necessary test items.
Example 2
Provided is a power lithium battery, which is prepared by the following steps:
the assembly process of the negative electrode, positive electrode, electrolyte, and battery was the same as in example 1, except that the separator was different.
Preparing a diaphragm: adding deionized water into polyacrylate, sodium carboxymethylcellulose, polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer according to the mass ratio of 6:1:10:83, stirring and dispersing uniformly in a stirrer, filtering by using a 150-mesh screen to obtain required slurry, coating the slurry on two end faces of the front face and the back face of the isolating membrane through gravure coating, and drying to form a continuous pure bonding layer. The three-layer polypropylene porous base membrane of 18um is selected for use to the substrate, the thickness of the pure tie coat of continuous type is 2um, and the value of its unilateral width is 10mm, and the blank space width of barrier film middle part is 600 mm.
Example 3
Provided is a power lithium battery, which is prepared by the following steps:
the assembly process of the negative electrode, positive electrode, electrolyte, and battery was the same as in example 1, except that the separator was different.
Preparing a diaphragm: adding the polyacrylate, the sodium carboxymethylcellulose, the polyvinylidene fluoride-hexafluoropropylene copolymer and the alumina into deionized water according to the mass ratio of 6:1:5:68:20, stirring and dispersing uniformly in a stirrer, filtering by using a 150-mesh screen to obtain required slurry, coating the slurry on two end faces of the front face and the back face of the isolating membrane through gravure coating, and drying to form a continuous bonding layer formed by mixing a pure polymer and an inorganic substance. The three-layer polypropylene/polyethylene/polypropylene porous basement membrane of 18um is selected for use to the substrate, the thickness of tie coat is 2um, and the value of its unilateral width is 10mm, and the blank space width of barrier film middle part is 600 mm.
Example 4
Provided is a power lithium battery, which is prepared by the following steps:
the assembly process of the negative electrode, positive electrode, electrolyte, and battery was the same as in example 1, except that the separator was different.
Preparing a diaphragm: adding deionized water into polyacrylate, sodium carboxymethylcellulose, polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer according to the mass ratio of 6:1:10:83, stirring and dispersing uniformly in a stirrer, filtering by using a 150-mesh screen to obtain required slurry, coating the slurry on two end faces of the front face and the back face of an isolating membrane by using a gravure roller with an improved engraving area, and drying to form a discontinuous point-shaped pure bonding layer, wherein the coverage rate in a coating area is 60%. The substrate chooses the porous basement membrane of 18 um's individual layer polypropylene for use, the thickness of the pure tie coat of discontinuous type punctiform is 1.7um, and the value of its unilateral width is 15mm, and the blank space width of barrier film middle part is 600 mm.
Example 5
Provided is a power lithium battery, which is prepared by the following steps:
the assembly process of the negative electrode, positive electrode, electrolyte, and battery was the same as in example 1, except that the separator was different.
Preparing a diaphragm: adding deionized water into polyacrylate, sodium carboxymethylcellulose, polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer according to a mass ratio of 6:1:10:83, stirring and dispersing uniformly in a stirrer, filtering by using a 150-mesh screen to obtain required slurry, coating the slurry on two end faces of the front face and the back face of the isolating membrane by using a gravure roll with an improved engraving area, and drying to form a non-continuous strip-shaped pure bonding layer, wherein the coverage rate in the coating area is 60%, and an included angle formed by the strip-shaped bonding layer and the MD direction of the porous base membrane is 45 degrees. The substrate chooses the porous basement membrane of 18 um's three-layer polypropylene for use, the thickness of the pure tie coat of non-continuous type strip is 2.3um, and the value of its unilateral width is 7mm, and the blank space width of barrier film middle part is 600 mm.
Comparative example 1
Provided is a power lithium battery, which is prepared by the following steps:
the assembly process of the negative electrode, positive electrode, electrolyte, and battery was the same as in example 1, except that the separator was different.
A diaphragm: three-layer polypropylene porous base membrane with the thickness of 18um is adopted as the diaphragm.
Comparative example 2
Provided is a power lithium battery, which is prepared by the following steps:
the assembly process of the negative electrode, positive electrode, electrolyte, and battery was the same as in example 1, except that the separator was different.
Preparing a diaphragm: adding deionized water into polyacrylate, sodium carboxymethylcellulose, polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer according to the mass ratio of 6:1:10:83, stirring and dispersing uniformly in a stirrer, filtering by using a 150-mesh screen to obtain required slurry, coating the slurry on the front surface and the back surface of an isolating membrane by gravure coating, and drying to form a continuous pure bonding layer with the two surfaces fully covered. The substrate chooses the porous basement membrane of 18 um's three-layer polypropylene for use, the thickness of the pure tie coat of continuous type is 2 um.
The performance of the lithium ion batteries provided in examples 1 to 5 and comparative examples 1 to 2 was examined:
1. and (3) testing static electricity of a diaphragm gluing area: the electrostatic value of the coated area of each test sample was measured using a SIMCO FMX-004 electrostatic field tester, and the average value was calculated for each set of samples repeated 5 times.
2. Testing the bonding force between the glue coating area and the lithium battery cathode: cutting 5 rectangular sample strips with the thickness of 10mm x 200mm in an isolation film coating area, cutting 5 rectangular sample strips with the thickness of 15mm x 220mm in a manufactured negative pole piece, respectively taking an isolation film and a negative pole piece, hot-pressing the coated isolation film and the negative pole piece together under the composite conditions of 2.0Mpa, 90 ℃ and 60 seconds, fixing one end of the negative pole piece on an upper clamp of a universal tensile machine, fixing the isolation film on a lower clamp of the tensile machine, testing the bonding force between the negative pole piece and the coated isolation film at a constant speed of 50mm/min, repeating the steps for 5 times in each group of samples, and calculating the average value of the samples.
3. Testing the bonding force between the gluing areas: cutting 10 rectangular sample strips with the thickness of 15mm x 220mm in the coating area of the isolating membrane, hot-pressing two same glued isolating membranes together under the compounding conditions of 2.0MPa, 90 ℃ and 60 seconds, fixing one end of one isolating membrane on an upper clamp of a universal tensile machine, fixing the other isolating membrane on a lower clamp of the tensile machine, testing the bonding force between the glued isolating membranes at a constant speed of 50mm/min, repeating the steps for 5 times for each group of samples, and calculating the average value of the samples.
4. Counting the battery assembly yield: and counting the process of preparing the lithium ion battery by the isolating film, counting the number of finished products of 100 batteries by taking the requirement of the delivered product as a standard, and calculating to obtain the finished product ratio.
5. And (3) testing the cycle performance of the battery: taking a lithium ion battery prepared by the isolating film as a sample, carrying out cycle test on the battery at the charging and discharging rate of 1C/1C under the environment of 25 ℃, and calculating the discharging capacity retention rate of the battery at the 1000 th cycle of each group.
6. The method is used for testing the vibration reliability of the lithium battery pack of the power battery according to the ISO12405-1:2011 standard, and mainly simulates random or regular vibration caused by various factors in the using process of the power battery, so that the service performance and the safety of the power battery are reduced.
The test results are shown in Table 1.
Table 1 results of performance testing
Figure BDA0002524788410000161
From the above detection results, for the square lithium ion battery with thickness, width and length of 25mm, 65mm and 610mm, respectively, the larger external dimension, especially the longer length, is a great challenge to the reliability and safety of the lithium battery manufacturing process and long-term use. As can be seen from table one, in comparative example 1, since the glue is not applied to both sides, the fixing effect of both ends cannot be realized, the yield of the battery cell assembly is low, and the process efficiency and the cost requirement of the battery cell are seriously affected. Secondly, in subsequent cycle and vibration tests, the capacity retention rate and the anti-vibration performance of long-term cycle are low due to the phenomena of short circuit and micro short circuit caused by possible relative motion of the positive pole piece and the negative pole piece. For comparative example 2, the separator was coated with a full-coverage polymer, and the presence of a large amount of polymer on the surface of the separator seriously affected the conductivity of lithium ions in the normal operating state of the lithium battery, increased the electrochemical resistance of the battery, and further led to the degradation of long-term cycle performance. In embodiment 1, two-side coating is performed, and the adhesive coating area of the isolation film has a high adhesive force with the battery negative electrode plate and the adhesive coating area, but the adhesive coating area only coats one surface of the isolation film, so that the fixing effect on two ends of the long battery cell is insufficient, and under extreme use conditions, a short circuit or a micro short circuit phenomenon caused by relative movement of the positive electrode plate and the negative electrode plate is easy to occur. For embodiment 2, the two-side gluing process is performed on the isolation film, but due to the relationship between the special structure and the surface static electricity, the rolling length can only reach 1000 meters, otherwise, local deformation caused by overlarge stress of the rolling end face occurs, the use of the isolation film in the battery assembling process is seriously influenced, meanwhile, due to the higher static electricity of the end face, dust particles in a workshop are easily adsorbed, the smooth spreading of the isolation film in the battery assembling process is influenced, the battery assembling yield is greatly improved, and the requirements on product rate and manufacturing cost control during mass production cannot be met. In embodiment 3, the inorganic oxide is added to the polymer coating formula, so that under the condition that a certain adhesion force between the adhesive coating area of the isolating film and the adhesive coating area of the battery negative electrode plate is maintained, the battery assembly yield can reach more than 99% due to the great reduction of static electricity on two sides, the production efficiency is greatly improved, the cost is reduced, meanwhile, due to the good fixing effect of the two ends, the structural stability of the lithium battery cell under normal and extreme conditions is ensured, and the capacity cycle retention rate and the anti-vibration test pass rate are high. For embodiments 4 and 5, due to the adoption of the end face discontinuous coating process, the bearing stress of the gluing superposition area is dispersed during the rolling of the diaphragm, so that the rolling length of the isolating diaphragm with glue applied to two sides is prolonged by 1000 meters, the efficiency in the large-scale use process is greatly improved, and the cost is reduced. Meanwhile, the adhesive force among the adhesive coating area of the isolating film, the negative pole piece of the battery and the adhesive coating area also keeps certain strength, and the effect of fixing the end face of the long battery cell is achieved, so that the long-term circulating capacity stability and the anti-vibration test result of the battery are reflected.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (16)

1. The battery cell is characterized by comprising a positive plate, a negative plate and a diaphragm; the separator includes a porous base film and a bonding layer;
along the preset direction of the porous base membrane, the surface of the porous base membrane comprises a middle blank area and coating areas at two ends;
the bonding layer is coated on the coating areas at two ends;
the negative plate is arranged on one side of the diaphragm, and two ends of the negative plate are bonded on the bonding layer coated on the surface of the diaphragm;
the positive plate is positioned on the other side of the diaphragm, and the positive plate is overlapped with the blank area of the diaphragm;
the preset direction is perpendicular to the MD direction of the diaphragm;
the size of the coating area in the preset direction is between 2mm and 15 mm; the blank area is followed the ascending size in the direction of predetermineeing is between 50mm ~1200 mm.
2. The electrical core of claim 1, wherein the bonding layer has a thickness in a range from 0.5 μ ι η to 4 μ ι η.
3. The electrical core of claim 1, wherein the bonding layer is a continuous coating layer or a discontinuous coating layer.
4. The electrical core of claim 3, wherein, along the predetermined direction, the discontinuous coating layer comprises a plurality of spaced stripe-shaped, dot-shaped, block-shaped, or curved coating layers;
the direction perpendicular to the preset direction is the MD direction, and when the discontinuous coating layer is a strip coating, an included angle formed between the strip coating and the MD direction is 10-170 degrees, but not 90 degrees.
5. The cell of claim 3, wherein the bonding layer is a discontinuous coating layer, and the coverage of the bonding layer in the coating region is between 10% and 90%.
6. The cell of claim 5, wherein,
the coverage rate of the bonding layer in the coating area is between 40% and 80%.
7. The cell of any of claims 1 to 6, wherein the material of the bonding layer comprises an organic material;
the organic matter is at least one selected from polyacrylate, polyacrylic acid, polyacrylate, styrene butadiene rubber, epoxy resin, amino resin, polyamide, polyethyleneimine, polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene copolymer and polyvinylidene fluoride-tetrafluoroethylene copolymer.
8. The electrical core of claim 7, wherein the raw material of the bonding layer further comprises at least one of sodium carboxymethyl cellulose and sodium alginate.
9. The battery cell of claim 7, wherein the organic matter accounts for 10 to 100 wt% of the total weight of the bonding layer.
10. The battery core according to claim 7, wherein the raw material of the bonding layer further comprises an inorganic substance, and the inorganic substance is one or more selected from alumina, titanium oxide, zinc oxide, calcium oxide, magnesium oxide, zirconia and boehmite.
11. The battery cell of claim 10, wherein the inorganic substance has a particle size D50 in a range of 0.1 to 2.0 μm.
12. The battery cell of claim 10, wherein the inorganic substance is 0 to 90 wt% of the total weight of the bonding layer.
13. The cell of any of claims 1 to 6,
the porous base membrane is a single layer; the material of the porous base membrane is selected from one or more of polyethylene, polypropylene, polyethylene terephthalate, polyamide, polyimide and PET non-woven fabrics; or
The porous base membrane is multi-layer; the porous base film is made of polyethylene and/or polypropylene with different molecular weights and different melt indexes.
14. The electrical core of claim 13, wherein the porous base film has a thickness in a range from 5 μ ι η to 30 μ ι η.
15. The cell of claim 13, wherein the porous base film has a porosity in the range of 20% to 70%.
16. A lithium power battery, characterized in that it comprises a cell according to any of claims 1 to 15.
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